1 files changed, 117 insertions, 0 deletions
diff --git a/src/backend/optimizer/util/ordering.c b/src/backend/optimizer/util/ordering.c
new file mode 100644
index 00000000000..3dffbff9f3c
--- /dev/null
+++ b/src/backend/optimizer/util/ordering.c
@@ -0,0 +1,117 @@
+/*-------------------------------------------------------------------------
+ *
+ * ordering.c--
+ *    Routines to manipulate and compare merge and path orderings
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/optimizer/util/Attic/ordering.c,v 1.1.1.1 1996/07/09 06:21:38 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "optimizer/internal.h"
+#include "optimizer/ordering.h"
+
+
+/*    
+ * equal-path-path-ordering--
+ *    Returns t iff two path orderings are equal.
+ *    
+ */
+bool
+equal_path_path_ordering(PathOrder *path_ordering1,
+			 PathOrder *path_ordering2)
+{
+    if (path_ordering1 == path_ordering2)
+	return true;
+
+    if (!path_ordering1 || !path_ordering2)
+	return false;
+
+    if (path_ordering1->ordtype == MERGE_ORDER &&
+	path_ordering2->ordtype == MERGE_ORDER) {
+
+	return equal(path_ordering1->ord.merge, path_ordering2->ord.merge);
+
+    } else if (path_ordering1->ordtype == SORTOP_ORDER &&
+	       path_ordering2->ordtype == SORTOP_ORDER) {
+
+	return
+	    (equal_sortops_order(path_ordering1->ord.sortop,
+				 path_ordering2->ord.sortop));
+    } else if (path_ordering1->ordtype == MERGE_ORDER &&
+	       path_ordering2->ordtype == SORTOP_ORDER) {
+
+	return (path_ordering2->ord.sortop &&
+		(path_ordering1->ord.merge->left_operator ==
+		 path_ordering2->ord.sortop[0]));
+    } else {
+
+	return (path_ordering1->ord.sortop &&
+		(path_ordering1->ord.sortop[0] ==
+		 path_ordering2->ord.merge->left_operator));
+    }
+}
+
+/*    
+ * equal-path-merge-ordering--
+ *    Returns t iff a path ordering is usable for ordering a merge join.
+ *
+ * XXX	Presently, this means that the first sortop of the path matches
+ *    	either of the merge sortops.  Is there a "right" and "wrong"
+ *    	sortop to match?
+ *    
+ */
+bool
+equal_path_merge_ordering(Oid *path_ordering,
+			  MergeOrder *merge_ordering)
+{
+    if (path_ordering == NULL || merge_ordering == NULL)
+	return(false);
+
+    if (path_ordering[0] == merge_ordering->left_operator ||
+	path_ordering[0] == merge_ordering->right_operator)
+	return(true);
+    else
+	return(false);
+}
+
+/*    
+ * equal-merge-merge-ordering--
+ *    Returns t iff two merge orderings are equal.
+ *    
+ */
+bool
+equal_merge_merge_ordering(MergeOrder *merge_ordering1,
+			   MergeOrder *merge_ordering2)
+{
+    return (equal(merge_ordering1, merge_ordering2));
+}
+
+/*****************************************************************************
+ *
+ *****************************************************************************/
+
+/*
+ * equal_sort_ops_order -
+ *    Returns true iff the sort operators are in the same order.
+ */
+bool
+equal_sortops_order(Oid *ordering1, Oid *ordering2)
+{
+    int i = 0;
+
+    if (ordering1 == NULL || ordering2 == NULL)
+	return (ordering1==ordering2);
+    
+    while (ordering1[i]!=0 && ordering2[i]!=0) {
+	if (ordering1[i] != ordering2[i])
+	    break;
+	i++;
+    }
+
+    return (ordering1[i]==0 && ordering2[i]==0);
+}